Electric elevator



. 25 of rotation.

UNITED STATES PATENT OEEIcE.

NILS O. LINDSTROM, OF UNION COURSE, ASSIGNOR TO A. B. SEE MANUFAC-TURING 00., OF BROOKLYN, NEXV YORK.

ELECTRIC ELEVATOR.

SPECIFICATION forming part of Letters Patent No. 538,377, dated April80, 1895.

Application filed February 26, 1895. Serial No. 539,725. (No model.)

To aZZ whom it may concern.-

Be it known that 1, Nine 0. LINDSTROM, a citizen of the United States,residing in Union Course, in the county of Queens and State of New York,have invented certain new and useful Improvements in Electric Elevators,of which the following is a specification.

This invention relates to electric elevators.

It has for its object a simplification of the IO controlling apparatusby which the move ments of the car are regulated and to permit the speedof the car to be varied smoothly and gradually.

The invention is carried out by providing in the car controlling devicesfor reversing the driving electric motor and a switch 01' othercircuit-controller for varying the strength of the magnetic field of themotor, the latter being automatically rendered inoperative to weaken themagnetic field when the car is heavily loaded. The gradual increase ofspeed is attained by decreasing the field-magnet strength of the drivingmotor, thereby permitting the latter to assumeahigher rate I preferablymake both the device for controlling the direction of movement of thecar and that for graduating its speed electric in chrracter, thoughmechanical devices for changing its direction of movement 0 might beemployed in connection with my improvement for varying the speed withoutdeparting from the scope of my invention in the latter particular. Iprefer, also, to vary the strength of the field-magnet by means of 5 anauxiliary and independent field-magnet coil which is reversely woundwith respect to the main field-magnet coil. At or near the motor isprovided a device for automatically opening the circuit of thespeed-regulating 4o coil when the motor is loaded to its full capacity,which thereby renders the speed-controller in the car dead irrespectiveof its actuation by the attendant, when the car is heavily loaded, andwhen, for that reason, it

requires a maximum field-magnet strength to move its load.

My invention comprises a graduating controller on the car combined withmeans for rendering it impotent to change the magnetic 5o condition ofthe motor when the latter is fully loaded. More specifically speaking itcomprises a magnetic regulator in the motor-circuit which opens thegraduating branch or cir cuit when a heavy current is flowing throughthe motor, as at low speeds and heavy loads, an organization whichpositively prevents a car attendant from incapacitating the motor forits maximum duty.

It also comprisesa particular mode of graduating the motor speed byclosing a circuit through a differential field-magnet winding, therebypermitting a reduction of field-magnet strength andconsequentlyincreased armature speedwithoutvariation of the strength ofthe field-magnet current.

It also comprises means on the car for gradually varying the effect ofthe differential field-magnet winding.

The several features of novelty will be more particularly hereinafterdescribed, and will be definitely indicated in the claims appended tothis specification.

In the accompanying drawing, which illustrates the invention, is showndiagrammatically a system embodying my improvements.

1 represents an elevator car, in which is mounted a switchboard providedwith a switch 2 connecting with one side of a supply circuit andprovided with a contact shoe which may be brought into engagement witheither So of two contacts 3, 3 and maintain contact therewith over adefinite range of movement. The outer end of the lever by continuedmovement sweeps over the contacts of a variable resistance 4 or a afterthe circuit has been closed and the contacts 3, 3 connect with separateconductors leading to the motor-regulating apparatus. All conductorsleading from the car may be grouped in a cable, each being suitablyinsulated, said cable leading to the basement or other point where themotor mechanism is installed. Contacts 3 and 3 control circuits leading,respectively, through two solenoids 6, G, which control a reversingswitch for the motor. The resistances 4, 4c 5 are in a circuit includingtwo contacts 7, 7 and a field-magnet winding 8, S reversely wound withrespect to the main field-magnet winding.

The armature circuit connects with the sup- 10o ply mains through acurrent-reverser 9 and circuit-closer 10.

Many different forms of the circuit-closing and reversing'apparatusmight be employed. That shown, which is simple and effective, is fullydescribed in a patent issued to Alonzo B. See and lValter L. Tyler, No.531,070, dated December 18, 189 1.

The circuit in which the auxiliary fieldmagnet coils are placed isopened or closed by a bridge-contact 11 controlled by a magnet orsolenoid 12 in the main motor-circuit, the armature or core of which ispreferably mounted upon the resistance-varying arm 13 of a rheostatwhich graduates the armature current. The solenoid core is hung on apivoted rod 14, journaled on the arm 13 and when the motor circuit isopen bears on a stud pin 15 whichholds it away from contacts 7, 7. \Viththis construction the core of the solenoid may be raised when anexcessive current is flowing through its coil so as to open the circuitat 7, 7. The auxiliary field-magnet coils 8, 8 are thus under control ofthe car attendant only when the current flowing through the solenoid 12is insufficient to lift the core and open the speedgraduating circuit.When the car is heavily loaded the motor will require its fullfield-magnet strength to lift the load, and, obviously, under suchcircumstances, the attendant should be incapacitated from weakening thetractive effort of the motor, if through ignorance or carelessness heshould attempt to do so. Under such circumstances the motor will operateat comparatively slow speed and the armature and field-magnet will bedrawing a maximum supply of current. The solenoid 12 will therefore befully energized and bylitting its core will open the speed-graduatingcircuit, thus putting it beyond the power of the attendant to vary thefield-magnet strength by actuation of the switch. W'hen, however, thecar has a lighter burden the motor armature will take a higher speedthus developing a greater counter-electro-1notive-force and drawing alighter current. The lifting power of the solenoid 12 will then beinsufficient to sustain the core and the contacts 7, 7 will beautomatically bridged. Then the attendant by operating the switch button4 can weaken the field-magnet of the motor and increase its speed. So,also, in stopping the car the act is rendered smoother or more gradualsince the first step is to gradually strengthen the field-magnet therebyslowing down the motor and then by cutting in resistance and finallyopening the circuit bring the car to a state of rest.

It will be understood that the graduating effect due to the auxiliaryfield-magnet coil may be limited so that it can only occur when thearmature has a certain speed and need not necessarily occur after thearm 13 has finished its traverse, since the solenoid 12 and the core maybe so calculated that the latter will be supported when the currentattains a desired value.

The circuitcloser and reverser for the motor comprise a pivoted bar 16,16, the two sides of which are insulated from each other, and bearrespectively in constant engagement with contact strips 17, 17 whichconnect through the circuit-closer with the supply mains.

The armature brushes connect, respectively, with contacts 18, 18 and 19,19, solenoid 12 and rheostat 20 being included in the armature circuit.The two sides of the supply circuit connect with contacts 21, 21, twoco-op'erating contacts 22, 22 being connected with the contact strips17, 17. The contacts 21, 21 and 22, 22 are in operative relation to twoinsulated metallic bridges 23, 23, by which, when the solenoid 6 or 6 isenergized, the circuit will be closed. A rheostat controlling solenoid 21-,the core of which may be connected with a dash-pot 25, is connectedwith contact 22, so that when the circuit is closed the solenoid will beenergized.

The operation of the system is as follows: The attendant operates theswitch-lever so as to connect contact 3 or 3, accordingly as he wishesto go up or down, thereby energizing the corresponding solenoid 6 or 6by acircuit from one supply main 26, conductor 27 of the car, cableconductor 28 or 28 of said cable, the corresponding solenoid andconductor 29 to the opposite supply main 30. Arm 16, 16, will he therebytilted, engaging at its two sides, I will say, contacts 18, 19,simultaneously circuit-closing lever 31 being depressed andbridge-contacts 23, 23 engaging their co-opcrating contacts 21, and 21,22. The fieldmagnet circuit of the motor is then closed over the pathfrom main 26 by conductor 32, contact 21, bridge 23, contact 22,conductor 33, main field-magnet coils, conductor 31-, contact 22,bridge'piecc 23, contact 21 and conductor 35 to the opposite supply main30. The armature circuit will be closed by way of conductor 32, contacts21, 22, contact strip 17 of the reversing switch, across the arm 16 atreversing switch to contact 19, thence by conductor 36 to the arm 13 ofthe rheostat', through the coils of the rheostat 20, solenoid 12, to andthrough the armature, thence by conductor 37 to contact 18, switch arm16, contact 17, contact 22, across bridge-piece 23 to contact 21, andthence by conductor 35 to the oppo site supply main. It solenoid 6 hadbeen actuated, thereby bringing contacts 18, 19 into action, the currentthrough the armature would have been reversed, since the lower brush ofthe armature would then be connected with the side 26 of the supplycircuit. The circuit having been closed,the armature rises in speed anda gradually increasing current is caused to flow through it by theslowly lifting core of the solenoid 24-. When the speed is suflicientlyhigh the current strength weakens and the points 7, 7 are automaticallybridged. The continued movement of the switch-lever by the attendantthen closes the circuit of the differential coil, thereby weak- ICCening the field-magnet and giving the motor a further increment ofspeed. Then as the switch-lever continues its movement the current inthe auxiliary coil is gradually in creased, thus further and graduallyweakening the motor field and giving it a gradually accelerating speedup to a maximum. If, however, the car has a heavy load its heavy draftof current will raise core|12 and thus open the circuit of the auxiliarycoil independently of the attendant and render it impossible for him toreduce the tractive effort of the motor.

It will be evident that in stopping the car the attendant, by firstcutting out resistance at 4 or 4 and thereby strengthening thefieldmagnet before opening the circuit, may produce a very steady andgradual decrease of speed; and thus in stopping or starting suddenchanges of speed, which are very unpleasant, are avoided.

Any suitable form of brake to hold the car at a landing may be employed.1 have not deemed it necessary to describe such, as it forms no part ofmy improvements.

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent, is

1.. An electric elevatorcomprising a shuntwound driving electric motor,means on the car for controlling the motor-circuit, an auxiliaryreversely-wound motor coil, and a switch on the car connecting it incircuit to graduate the speed.

2. An electric elevator comprising a driving electric motor, means onthe car for controlling the motor-circuit, an auxiliary reverselywoundfield-magnet coil, a switch on the car for connecting it in circuit, anda variable resistance for gradually varying the effect of the auxiliarycoil.

3. An electric elevatorcomprising a driving electric motor, means on thecar for controlling the motorcircuit, a motor rheostat for graduatingthe speed, an auxiliary reversely- Wound field-magnet coil adapted to becut into circuit, and a variable resistance for graduating the effect ofthe auxiliary coil.

4. An electric elevator comprising a controller carried by the car forregulating the direction of rotation of the driving motor, a switch orcircuit-closer in the car for varying the field-magnet strength, andmeans for preventing such change of strength when the motor is carryinga maximum load.

5. An electric elevator comprising a controller carried by the car forregulating the direction of its movement, a switch or circuitcloser onthe car controlling a motor coil for varying the field-magnet strengthof the driving motor, and a magnetically controlled circuit-breaker foropening the circuit of such coil independently of the car circuit-closerwhen the motor is carrying amaximum load.

6. An electric elevator comprising a controller on the car forregulating the direction of its movement, a switch or circuit-closer onthe car controlling an auxiliary coil for varying the field-magnetstrength of the driving motor, and a magnetically controlledcircuitbreaker in the motor-circuit for opening the circuit of theauxiliary coil independently of the car circuit-closer when the motor iscarrying a maximum load.

7. An electric elevator comprising a controller on the car forregulating its direction of movement, a switch or circuit-closer on thecar in circuit with an auxiliary reverselywound field-magnet coil, and amagnetic circuit-breaker in the motor-circuit for opening the circuit ofthe auxiliary coil independently of the car circuit-closer when themotor is carrying a maximum load.

8. An electric elevator comprising a controller on the car forregulating its direction of movement, a switch or circuit-closer on thecar controlling a circuit including a differential field-magnet coil, amagnetic circuitbreaker in the motorcircuit for opening the circuit ofthe differential coil upon great increase of current strengthin themotor-circuit, and means for normally opening or closing the circuitofthe differential coil at all points except the attendants circuit-closerwhen the motor-circuit is opened or closed.

9. An electric elevator comprising a controller on the car forregulating its direction of movement, a switch or circuit-closer on thecar in a circuit including part of the fieldmagnet winding, whereby thefield-magnet strength may be varied, an electromagnetic devicecontrolling a circuit-breaker for opening said circuit when the motor isheavily loaded, said device being in the main motorcircuit andconnections between the circuitbreaker and the motor apparatus wherebythe field-magnet strength can only be cut down after the motor circuithas been closed.

In testimony whereof I have hereunto subscribed my name this 2lst day ofFebruary, A. D. 1895.

NILS O. LINDSTROM.

lVitnesses:

ALONZO B. SEE, PHILIP KOMPFF, J r.

ICC

